1. Field of the Invention
The present invention relates to an autostereoscopic display apparatus comprising a matrix display panel having an array of display elements which are arranged so as to extend in rows and columns in a row and column direction respectively and in groups with each group comprising N adjacent display elements in the row direction where N is a number greater than two, and optical director means comprising a plurality of optical director elements each of which is associated with a respective group of display elements for directing the outputs of the display elements in mutually different angular directions.
2. Description of the Related Art
Such an apparatus is described in EP-A-0625 861. The matrix display panel in this apparatus comprises an active matrix (TFT type) LC (liquid crystal) display panel acting as a spatial light modulator. It is usual in conventional, ordinary view, types of active matrix LC display panels comprising a planar array of display elements to space the display elements apart in columns at regular intervals and to provide a black mask over the intervening spaces which shields the switches, comprising TFTs from light and which extends between adjacent columns of display elements, and between adjacent rows, to mask address conductors and enhance contrast. The display element layout in a standard direct view or projection type active matrix LC display panel is designed to create a perfectly repetitive pattern at small enough pitch to go undetected by the eye. However, when such panels are used for autostereoscopic display purposes with optical director means such as lenticular screens, microlens arrays, or the like to create a 3D display, the black mask pattern gives rise to visible artifacts. In the apparatus described in this specification, the display elements of each group are arranged so as to be substantially contiguous with one another in the row direction in order to reduce problems with display artifacts caused by the black masking. When viewing a conventional LC display panel with regularly-spaced display elements through the optical director means, which in this known apparatus comprises, for example, a lenticular screen having a plurality of parallel lenticules each of which is disposed over a plurality of adjacent columns of display elements in which the display elements of an associated group lie and provides output light beams from the respective columns of display elements associated with the lenticule, then vertical (columnwise) portions of the black mask are also imaged by the lenticule such that the images from adjacent columns of display elements are separated by dark regions and the display output lacks continuous parallax. As a viewer moves his head to perceive a 3D display, in which each column of display element provides a vertical slice of a 2D image, the successive, different, views seen by the viewer are interrupted by the imaged black mask. The grouping of the display elements in substantially contiguous manner helps to overcome this problem as substantial continuous vertical black mask portions are no longer present between adjacent columns. In one embodiment described in EP-A-0 625 861, this is achieved by arranging the display elements, which are generally rectangular in shape, such that one display element is offset with respect to the neighboring display element in the column direction with a vertical edge of the one display element being substantially aligned in the column direction with the adjacent vertical edge of the neighbouring display element. In another described arrangement, capable of providing only one stereoscopic view, each group comprises just two display elements from two adjacent columns of display elements and aligned in the row direction and in which the width of the gap between these adjacent columns is comparatively small.
A similar problem would exist even if the black mask portions between adjacent columns of display elements were to be omitted except that, rather than there being dark regions visible between successive views caused by black mask portions there would be visible artifacts due to the unmodulated regions of the LC layer then exposed.